1 Answer from the Community

The screen in this mode is an exact duplicate of whatever is displayed on the iPad/iphone.

On an iPhone 5, which I just tested for you, the image is very slim and central when the iPhone is vertical, but when the device is horizontal it near-fills the screen.

Note that the display doesn't show the map at a different size to your device (This may sound an odd thing to suggest, but Netflix, for example, outputs video to a separate screen, with a different resolution to that shown on the iOS device- I believe this is because there is a different path through the display chips for hardware accelerated video)